A long time since my last update (that's a good thing!) and the car is still running nicely. It starts on the first turn even at -4 degrees (brr) and although I've had trouble with the door rubbers sticking the doors shut in the cold and the tyres are NOT the best for cold weather the car has been otherwise reliable. Waiting for the summer months are:
Trackrod ends and possibly droplinks
Four new tyres
Cam belt
Gearbox oil change (engine oil was done just before the winter)
Coolant change
LHM change and filter clean (should I bother with hydraflush ?)
That's about it really. Touch wood the car has been running nice and reliably.
The brake pad warning light has started flickering on intermittently but I'm pretty sure the pads had plenty of thickness left when me and Richard were looking at the lower balljoint so I'm thinking its probably a misrouted wire chafing ? Far too cold and wet to be doing non-essential jobs outside at the moment and my garage is not surprisingly full to the brim with renovation left overs and garden tools that are waiting for a garden shed to call home.
I came across an interesting article I wanted to share that backs up some observations I have made with both my V6's. Some of you might recall that among the issues of the Silver problem child that a lean mixture is something I battled with for which I could never find a definite cause for. In the end I worked around it by changing the fuel pressure regulator from 3 bars to 3.5 bars which did help a lot, and at higher RPM that engine ran like a bat out of hell even when I sold it, in fact to my disapointment the foot to the floor higher RPM acceleration of this new V6 has never been as good as the old one.... after reading this article, I think bumping the fuel pressure up on the old one may explain it the difference between the two cars...
http://www.groups.tr-register.co.uk/wes ... pdate.html
In short, Ethanol is to blame for older petrol engines running too lean! This is not something I had considered before even though I was aware that ethanol was added to most petrol today. Here are some quotes from the article:
So basically an old petrol injection system that is not specifically designed for Ethanol blends, which includes the fairly primitive by today's standards Bosch MP 7.0 ECU on the ES9J4, will run leaner than it should in open loop mode on Ethanol enriched fuels and get progressively leaner the higher the concentration of Ethanol.Drivability Issues
The ideal fuel/air ratio for a petrol engine (Stoichiometric Air/Fuel Ratio) is between 14.5 & 14.7 to 1. That is 14.7 parts air to 1 part fuel by volume. For pure Ethanol this ratio is between 8.9 & 9 to 1. (9 parts air to 1 part fuel).
This can partly be explained because Ethanol contains 35% Oxygen by weight and therefore will naturally ‘lean-off’ the fuel/air mixture.
Even at only 5% mixture, Ethanol will alter the correct fuel/air ratio and lead to unadjusted engines running weak.
To further add to the problem, vaporisation can lead to incorrect fuel metering and a further ‘leaning’ effect (Enleanment).
Even modern engines using electronic fuel injection systems can be susceptible to this phenomenon. Most modern vehicles use a ‘closed loop’ system to maintain and monitor perfect fuel/air ratio (Lambda 1). This is achieved by the use of an Oxygen (or Lambda) sensor in the exhaust. This is active under idle and light cruise conditions, however under heavier load conditions (WOT ‘wide open throttle’) the system reverts to open loop and relies on the map in the engine ECU. It is unlikely that under these conditions even a modern engine will be able to compensate for the necessary change in fuel/air ratio required when using a fuel other than 100% petrol. Any pinking or knocking caused by a lean mixture may be detected by a knock sensor (if fitted) and lead to reduced engine power and possibly illuminate the M.I.L. (Malfunction indicator lamp) depending on the sophistication of the engine management system. Some manufacturers already produce vehicles that can run on fuel with as much as 85% Ethanol mixture (E85) proving that Ethanol is suitable as a fuel for internal combustion engines provided that it is designed with this fuel in mind but it is unlikely that carburettored vehicles or those fitted with mechanical or early electronic fuel injection will be able to make sufficient adjustment to the mixture strength while running on E10 (which will be here in 2013).
Ethanol has a higher volatility than petrol and therefore is vaporises more readily. This can lead to ‘vapour lock’ in components such as carburettors and fuel pumps etc, particularly if allowed to heat soak. This means that a hot engine that is switched off will heat soak the fuel (which it does anyway) and cause starting problems if the engine is restarted whist still hot. Some vehicles may suffer from vapour lock whilst running, especially on hot days, leading to loss of power and cutting out.
In closed loop mode - when idling, cruising with a light throttle, or passing an emissions test, (!) the oxygen sensor will allow the ECU to compensate for the change in fuel and bring the mixture back to what it should be, however open loop mode will be lean. This means flat spots and hesitation, and reduced power when accelerating hard.
When this article was written (before 2013) and when I had my first V6 the UK was still using E5, but by now we are using E10 so the situation will have gotten even worse.
Also not all fuels have had Ethanol added. Apparently all standard octane (95) fuels in the UK have added Ethanol and are probably E10 by now in 2016, however some of the high octane fuels do not have added Ethanol in some parts of the UK.
So it's quite possible that the performance difference I notice between different fuels is not just Octane rating but the Ethanol percentage, with lower Ethanol fuels performing better in the old engine due to the mixture not being as lean as a higher Ethanol fuel...
I normally use Shell V-Power but as the station is some distance away from where we live now and a new Esso opened up nearby I thought I'd give Esso's Synergy Supreme (97 octane) a try - and I was not impressed. It seemed OK at first but after a while I was really noticing the card did not seem happy, being quite noticeable sluggish. On the next fill I thought I would try Tesco's Momentum (99 octane) and within just a few miles it was back to its zippy self - as good if not better than the Shell V-Power. I have never tried the Tesco Momentum before but after this good experience and considering that it's cheaper than standard octane from most other suppliers I'll give it another try.
So what to do about the problem of E10 ? If the ECU maps could be reprogrammed to richen the open loop mixtures by the correct amount the card would run nearly as well on E10 as it would have on 100% petrol, however remapping is not a viable option on an ES9J4.
The other solution is to increase the fuel pressure, as I did on the old V6 by changing the fuel pressure regulator. It's a pretty standard Bosch vacuum operated fuel pressure regulator used in a lot of different cars, so I'm sure a 3.5 bar Bosch version will be available. The 3.5 bar regulator I fitted to the old V6 was a cheap after market one (about £30) which had some internal leakage so I wasn't very happy with that, so I would definitely be using an OEM Bosch one this time, even though they're around the £90 mark.
In closed loop mode the oxygen sensor will allow the ECU to compensate so it will still run at the correct mixture there and pass the emissions test, however the higher fuel pressure means that the open loop mixture will be proportionally richer, compensating for the leaning effect of the Ethanol. The fuel delivered increases by the square root of the pressure, so going from 3.0 to 3.5 bars is a ratio of 1.1666, take the square root is 1.08, so 3.5 bars will make the open loop mixture about 8% richer.
Another benefit from increasing the fuel pressure a bit is that chances of vapour lock when hot are reduced, as the higher pressures increase the boiling point of the fuel, so this would partly counteract the tendency of E10 to vapour lock.
So if you have an ES9J4 and want to squeeze the last drops of performance out of it, and taking into consideration that most fuels now days have Ethanol in them that weren't there when the engine was originally designed, consider fitting a 3.5 bar pressure regulator!
